The present invention relates generally to gas operated guns, and more particularly to gas powered semi-automatic rifles.
Since production began in the late 1950""s, over a million 0.30 caliber M-14 service rifles have been manufactured for the United States Armed Forces. Additionally, an uncounted number of M-14""s and variations thereof have been produced for commercial use and for use in foreign countries. Furthermore, numerous spare components have been produced and stockpiled for the M-14 and its variants such as the M1-A (hereinafter rifles of this design family are referred to as xe2x80x9cM-14xe2x80x9d). Though it is no longer used as a standard issue combat weapon in the U.S. military, police forces and foreign armed forces sometimes will still use the M-14. There are currently a large number of M-14 rifles that are stockpiled and sparsely used.
The M-14 is a semi-automatic and/or fully automatic weapon meaning that the rifle automatically reloads itself each time a round is fired. The M-14 includes a bolt that slides within a receiver to eject the spent cartridge and chamber a new round for firing. The receiver and bolt are located toward the butt end of the rifle where the trigger is located. The rifle also includes an operating rod that slides relative to the housing and is manually operable against the action of a return spring to facilitate manual sliding of the bolt and therefore loading of bullets into the receiver.
To provide the force and motion for mechanically driving the bolt within the receiver and carrying out the rifle""s cycle of operation, a gas operated rifle includes a gas cylinder assembly. The gas cylinder assembly temporarily stores and then utilizes a propellant gas charge which is generated in the barrel each time a round is fired. For the M-14 rifle, the gas cylinder assembly comprises a housing and a piston that in combination define a chamber that receives a working gas charge that is used to propel the piston and thereby power the bolt rearwardly through engagement with the operating rod. The gas cylinder assembly is located away from the receiver near the discharge end of the barrel where it is mounted directly under and parallel to the barrel. The piston of the gas cylinder assembly acts upon and is acted upon by the distal end of the operating rod. The operating rod includes an actuating face at its foremost distal end that is urged forwardly against the piston under the action of the return spring. To ensure proper engagement, the distal end of the operating rod is offset from the barrel at the same angular position in axial alignment with the gas cylinder assembly. For purposes of reference, a prior art M-14 rifle according to the above description is shown in FIGS. 1 and 2. Further details of a prior art M-14 rifle may also be had to The U.S. 0.30 Caliber Gas Operated Service Rifles; A Shop Manual Volumes I and II, Copyright 1995 by Jerry Kuhnhausen, or other similar gun operation manuals.
The time frame in which the rifle""s cycle of operation is completed appears to the rifle user to be almost instantaneous. Accordingly, the M-14 can be repeatedly fired as fast as the user can pull the trigger. To provide for mechanical repetition and to contend with the speeds and forces generated by the cycle of operation, the rifle components must be precisely located and accurately aligned with one another. Changing the pre-set locations and dimensions of these components poses the potential risk of adversely affecting the rifle""s operation.
Typically, the standard M-14 rifle has a barrel that is typically 23 inches in length measured by dropping a rod into the barrel butting up against the front face of the bolt in the foremost position, and measuring rod length at the front most end of the barrel without a flash suppressor or components mounted to the barrel end (e.g. stripped down). Unfortunately the length of the M-14 is a significant problem in applications where is desirable to have a short rifle. For instance, paratroopers often exit airplanes through narrow hatchways when making their jumps. Also, soldiers and/or police forces operating in urban settings often must travel down tight corridors, pass through narrow doorways, or swing around hallway corners. Likewise, soldiers must operate within the tight confines of a ship and pass through narrow hatchways such as those on a submarine. In these and other similar applications, the standard length of the M-14 is typically considered to be too much of a drawback to warrant consideration for use. In particular, because of the long length of the M-14 barrel, the end of the barrel or muzzle is prone to strike walls, hatchways, and other obstructions, thereby severely limiting the maneuverability of the soldier or officer. Due to this significant drawback, the M-14 is not a weapon of choice and is not frequently used, despite the fact that it is a readily available weapon that often exhibits superior reliability compared with other existing shorter rifles.
Merely cutting off the end of the barrel does not provide a sufficient solution, because the barrel may only be cut a small fraction to only about 16xc2xd inches before interfering with the position of the gas cylinder assembly and its engagement with the actuating face or distal end of the operating rod. Cutting off the gas cylinder assembly is not a realistic possibility either as that would remove the semi-automatic capabilities of the weapon and thereby create other more serious drawbacks. Hence, the M-14 rifle remains too long for use in many potential applications.
The present invention provides a gas operated, semi-automatic rifle, such as the M-14, with a shortened barrel functioning in conjunction with the existing design of most rifle components, with few design modifications and/or substitute parts. The shortened barrel supports the gas cylinder assembly at a different angular position with respect to the barrel axis than the directly underneath position where the gas cylinder assembly is currently located according to current design. Instead of engaging the actuating face at the distal end of the operating rod, the operating rod abuts against the gas cylinder assembly at a new position closer to the receiver end of the rifle, thereby eliminating the need of contact with the distal end of the operating rod. Accordingly, the length of the barrel previously needed to support the gas cylinder assembly in an end-to-end relationship with the operating rod can be greatly reduced, and thereby make the rifle more ergonomic and suitable for applications where a shorter rifle is desired or required.
The present invention also provides a method of retrofitting existing rifles with a kit comprising shortened barrels with a rearranged gas cylinder assembly. This makes the invention applicable to the large stockpiles of M-14 weapons currently in existence.
An advantage of the present invention is that it provides a shortened gas operated, semi-automatic rifle that can be built primarily from existing stockpiled rifles and rifle components. Another advantage of the present invention is that it provides an inexpensive method of retrofitting existing rifles by reusing many of the costlier components. The invention also contemplates the manufacture of entirely new shorter M-14 rifles in which the design of the vast majority of rifle components are unchanged, and therefore the well known reliability characteristics that have been long established for the M-14 rifle continue with immediate market recognition.